Collaroy Stormwater Outlet

This consultation has concluded."

Upgrading our critical stormwater infrastructure

The Collaroy Beach stormwater outlet was installed in the 1970s and its outer walls have deteriorated to the point that they now need replacing.

Read the news items below for the project background, options considered, how to be involved and project updates. You can also view the key documents in the library.


This consultation has concluded."
  • Work to commence in July 2014

    Council is planning to repair the existing stormwater outlet on Collaroy Beach.

    The existing pipe was built in the 1970s, and the outermost sections need replacement. Council consulted with the community on possible locations and replacement designs in 2012 and 2013. The replacement options looked at increasing the amount of water that could be carried in the pipe and therefore improving the drainage in some Collaroy streets. These options far exceeded the available budget and in September 2013 Council decided not to proceed with an entirely new replacement outlet due to cost. Since that time staff have been working on solutions for the broken outlet structure only.

    The repairs involve removing the existing exit distributor, four culvert sections and their supporting piles.  A new exit distributor, one new culvert section and new piles will be installed. This will shorten the outlet structure by approximately 10 metres. The new sections will incorporate a number of design changes to improve the performance of the structure, and will be of similar size to the current sections.

    Council decided not to proceed with an entirely new replacement outlet due to the excessive cost in September 2013

    It is expected that the replacement works will start in July 2014 and be completed by November 2014. Information will be available on the Current Works page. 

    by site admin 2 19 Feb 2014, 10:13 AM
  • Design to be reviewed

    On 24 September 2013 Council resolved that:
    A. Pursuant to Clause 178(1) (b) of the Local Government (General) Regulation 2005, Council decline to accept any of the tenders received for RFT 2013/026 - Major Works for the Construction of the New Collaroy Stormwater Outlet.
    B. Pursuant to Clause 178 (3) (a) of the Local Government (General) Regulation 2005, Council cancel the proposal for the contract.
    C. The feasibility of shortening the existing structure and replacing only the damaged components be investigated and, if applicable, invite a further tender for the new scope of works.

    Council Minutes 24 September 2013

    by site admin 1 04 Oct 2013, 02:06 PM
  • Media Release April 2013

    The design for the new stormwater outlet at Collaroy Beach has been released for comment.

    The existing pipe was built in the 1970s and needs replacing. Council consulted the community on possible locations and options for a replacement in 2012 and in June, resolved to replace the pipe at the current location.

    The proposed new outlet will be 2.1 metres in diameter and approximately 10 meters shorter than the current pipe and will be installed next to the current structure, which will then be removed. Under normal conditions most of the structure will be covered with sand. The visible section will be narrower with a shape that will minimise the impact of waves on the structure.

    The design and environmental assessments can be viewed online, at Council libraries and the Civic Centre. The public can comment until Friday 3 May. It’s hoped construction can start in November.

    by Site Co-ordinator 18 Apr 2013, 05:03 PM
  • New Design for Collaroy released

    The Collaroy Beach stormwater outlet was installed in the 1970s however wave action has damaged the outermost sections. After an extensive technical evaluation and community consultation process, Council decided in June 2012 that the new outlet should be located at the current site.

    The design for the new outlet has now been completed. You can view the new design  along with the Review of Environmental Factors  and a summary presentation. You can also view these documents at the Civic Centre or Libraries.

    Please forward any comments to Warringah Council, 725 Pittwater Road, Dee Why NSW 2099 or email by Friday 3 May 2013.

    by site admin 1 04 Mar 2013, 04:34 PM
  • Online Feedback Form 2012

    This survey has now closed.

    Thank you to those people that attended the On Site Information Session on Saturday 24 March. If you were unable to attend please complete the online feedback form with your thoughts on the two options.

    For more information on the options please read the discussion paper.

    by Site Co-ordinator 04 Apr 2012, 06:09 PM
  • Discussion Paper on Options

    The online forum has now closed.

    Council has developed a discussion paper outlining the pros and cons of the two options.

    Join the online forum to let us know what you think about the options.

    by Site Co-ordinator 20 Mar 2012, 11:09 AM
  • Join the Online Forum

    We'd like to know what you think about the two options. Click here for the online forum.

    by Site Co-ordinator 13 Mar 2012, 01:57 PM
  • Community Information Session


    Community Information Session

    Collaroy Beach – marquee located near Collaroy Surf Life Saving Club

    Saturday 24 March 2012

    11am – 2pm

    You can also join the online forum or call 02 9387 2600

    by Site Co-ordinator 13 Mar 2012, 11:39 AM
  • Background - Investigation of Alternatives

    The Collaroy outlet pipe provides an outlet for stormwater from the Collaroy catchment. The reinforced concrete structure extends some 85 meters from the seawall into the surf. It was last rebuilt in the 1970s, and its outer walls have deteriorated to the point that they now need replacing.

    Investigation of Alternatives

    Council previously assessed several options which included:

    •   Replacement outlet at current position
    •   Very short outlet (in the same position)
    •   Very long buried outlet (in the same position)
    •   Divert to existing pipe at southern end of beach (near rockpool)

    The objective of these studies was to evaluate, assess, and prepare designs to:

    • Ensure the safe and effective disposal of stormwater
    • Ensure that the new stormwater outlet does not restrict any future upstream flood alleviation works
    • Maintain water quality in the rockpool and beach area
    • Minimise any impact on the beach profile and form
    • Safely decommission and remove the existing outlet structure

    The studies also included geotechnical investigations, a review of environmental factors and cost assessments.

    Council is now looking at two of these previous options:

    • Middle beach option: Replace the existing stormwater outlet with a new one in the current location
    • South beach option: Relocate the stormwater outlet to a location adjacent to the ocean pool at the southern end of Collaroy Beach

    Both options are feasible, however there is no ‘perfect solution’ and Council understand that both plans involve some trade-offs.

    Council is consulting with the local community about both options for the Collaroy stormwater outlet and we are keen to answer questions and hear feedback from you. Community input is one of many considerations that will shape Council’s decision about how to proceed.

    by Site Co-ordinator 13 Mar 2012, 11:37 AM